• The Korean Journal of Physiology and Pharmacology
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• v.10 no.1
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• pp.1-6
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• 2006

To evaluate whether metformin restores leptin sensitivity in aged rats with leptin resistance, we measured leptin sensitivity in aged (2 year old) and adult (5 month old) rats after 4 weeks of treatment with metformin (300 mg/kg/D, mixing in drinking water), by measuring food intake, body weight and visceral fat losing effects. Leptin ($15{\mu}g/D$) was administered by intracerobroventricular (i.c.v.) infusion through osmotic minipump for 1 week. Metformin treatment decreased body weight and daily food intake in both adult and aged rats compared with their control rats, however, these effects were more prominent in aged rats than in adult rats. Anorexic and fat losing responses following i.c.v. leptin were attenuated in aged rats compared to adult rats. However, these responses of aged rats to leptin were restored by metformin treatment. Moreover, serum concentration of leptin in aged rats was significantly decreased by combined treatment with metformin and leptin. These results suggest that metformin enhances leptin sensitivity in aged rat model, and that combination therapy with metformin and leptin would be helpful for treatment of aging-associated obesity.

• The Korean Journal of Physiology and Pharmacology
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• v.12 no.3
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• pp.89-94
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• 2008

In order to reproduce chronic cerebral hypoperfusion as it occurs in human aging and Alzheimer's disease, we introduced permanent, bilateral occlusion of the common carotid arteries (BCCAO) in rats (Farkas et al, 2007). Here, we induced BCCAO in two different rat strains in order to determine whether there was a strain difference in the pathogenic response to BCCAO. Male Wistar and Sprague-Dawley (SD) rats (250-270 g) were subjected to BCCAO for three weeks. Kluver-Barrera and cresyl violet staining were used to evaluate white matter and gray matter damage, respectively. Wistar rats had a considerably higher mortality rate (four of 14 rats) as compared to SD rats (one of 15 rats) following BCCAO. Complete loss of pupillary light reflex occurred in all Wistar rats that survived, but loss of pupillary light reflex did not occur at all in SD rats. Moreover, BCCAO induced marked vacuolation in the optic tract of Wistar rats as compared to SD rats. In contrast, SD rats showed fewer CA1 hippocampal neurons than Wistar rats following BCCAO. These results suggest that the neuropathological process induced by BCCAO takes place in a region-specific pattern that varies according to the strain of rat involved.

• Journal of the Korean Society of Food Science and Nutrition
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• v.28 no.3
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• pp.670-676
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• 1999

The effect of exercise and/or high fat diet on carnitine status and carnitine palmitoyltransferase I(CPT I) level were investigated in Weanling Sprague Dawley rats. The rats were fed an AIN 76 diet or a modified high fat AIN diet, supplemented with 35% corn oil, for 31 days. During the 31 day period half of the animals in each dietary group were exercised on a treadmill for 90 minutes per day. Carnitine concentrations were determined in plasma and liver and CPT I mRNA levels were measured by Northern blot analysis with CPT I cDNA probe in livers of rats. Exercise rats gained less weight than non exercised rats during the study for high fat diet group. Exercise rats had a higher plasma acid soluble acylcarnitine and acid insoluble acylcarnitine concnetrations than non exercised rats for normal diet group. Exercise or high fat diet increased liver carnitine concentration, but a mixed effect was not shown. In exercised rats, CPT I mRNA levels increased significantly relative to those of nonexercised rats. CPT I mRNA levels also increased when compared high fat fed rats with those of normal diet fed rats. These data suggest that there is a correlation between carnitine concen trations and CPT I mRNA levels and that CPT I can be regulated at the transcriptional level by exercise and/or high fat diet.

• The Korean Journal of Physiology and Pharmacology
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• v.10 no.5
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• pp.283-287
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• 2006

Although estrogen is known to playa role in fatty acid metabolism, it remains unclear whether fatty acid oxidation in mature female rats differs from fatty acid oxidation in peri-pubertal young rats. In this study, we measured fatty acid metabolism in the skeletal muscles and livers of 5 and 50 weeks old male and female rats. The rate of palmitate oxidation in the liver and gastrocnemius red in the 50-week-old female rats were elevated as compared to the 5-week-old females, whereas there were no differences in the male rats. The rate of palmitate oxidation in the gastrocnemius red was correlated inversely with intra-abdominal fat mass in the 5-week-old male and female rats, whereas the palmitate oxidation rate was positively correlated with fat mass in the liver and gastrocnemius red in the 50-week-old rats. HOMA-IR and plasma insulin levels were positively correlated with intra-abdominal fat mass in the pooled 50-week-old male and female rats, but this correlation was not apparent in 5-week-old rats. In summary, the rate of fatty acid oxidation measured in the middle-aged adult female rats was significantly higher than those measured in the peri-pubertal young female rats. This difference may be attributed to the influence of ovarian hormones.

• Nutritional Sciences
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• v.8 no.1
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• pp.10-15
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• 2005

An increase in serum cholesterol is directly associated with high incidences of cardiovascular diseases (CVD) and atherosclerosis. Serum lipid profiles are highly dependent on dietary fatty acids and age. The purpose of this study was to examine the age-related effects of polyunsaturated/saturated fatty acid ratios and antioxidant supplementation under the control of the dietary peroxidizability index (PI) value on serum lipid profiles in rats. While the PI level of dietary fatty acids was controlled at 81.22, the P/S ratios of fatty acids were 0.38 and 4.81 (LP and HP). The diets were supplemented with a vitamin E 1000 mg/kg diet and a selenium 2.5 mg/kg diet (LPS and HPS). Female Sprague-Dawley rats ages 3 weeks (young) and 16 weeks (adult) were fed four different experimental diets for 4 weeks. The serum triglyceride concentration of LPS was significantly higher in young rats than in adult rats. The total-cholesterol concentration of LP and HPS were higher in young rats than in adult rats. The high-density lipoprotein-cholesterol (HDL-C) concentration of LP, LPS and HP was higher in adult rats than in young rats. The low-density lipoprotein-cholesterol (LDL-C) concentration was higher in young rats than in adult rats. T-C/HDL-C and LDL-C/HDL-C ratios were much higher in young rats than in adult rats. In conclusion, P/S ratios and antioxidant supplementation did not affect T-C/HDL-C and LDL-C/HDL-C ratios as risk factors of CVD in adult rats when we controlled the PI value in the diet Probably, the invisible and confounding effects of dietary PI value implicate the beneficial roles of dietary P/S ratios and antioxidants in CVD. Accordingly, controlling the dietary PI value may be advantageous to lower the risk of CVD in adult rats.

• The korean journal of orthodontics
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• v.21 no.3
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• pp.521-541
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• 1991

The purpose of this study was to investigate the growth changes of the mandible and associated structure in response to postural hyperpropulsion and changes after removal of postural hyperpropulsor. The experimental animals were four-week-old Sprague-Dawley males rats. The animals were worn the postural hyperpropulsor diurnally for 10 hours per day. The animals were sacrified after 1-week, 2-week, 4-week postural hyperpropulsion and 4-week postural hyperpropulsion 4-week removal period. The growth changes of rat mandible and associated structures following postural hyperpropulsion on the growing rat mandible were observed biometrically, radiographically and histologically. The finding were as follows. 1. The angle between the chief axis of the bone trabeculae in the condyle and the mandibular plane of rats observed for 4 weeks after worn the hyperpropulsor for 4 weeks was directed posteriorly as compared with that of control rats. 2. The ratio of mandibular length to maxillary length of experimental rats was higher than that of control rats. 3. The tooth axis of mandibular first molar of rats worn the postural hyperpropulsor for 4 weeks was mesially inclined as compared with control rats. 4. Histologically, the cartilage layer at the superior region of the condyle of rats worn the postural hyperpropulsor for 2 weeks appeared thicker than that of same aged normal rats, and generalized increase of the cartilage layer was shown on the condyle of rats worn the postural hyperpropulsor for 4 weeks. 5. There was no significant histologic difference between rats observed for 4 weeks after worn the postural hyperpropulsor for 4 weeks (8 week experimental rats) and same aged normal rats. 6. The newly formed bone at anterior region of articular fossa of rats worn the postural hyperpropulsor for 2 weeks and 4 weeks was thicker than that of same aged normal rats.

• Journal of Nutrition and Health
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• v.33 no.5
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• pp.517-523
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• 2000

The effect of dietary zinc deficiency and age on lipid peroxide level was investigaed in rats. Zinc level in serum and liver were also measured. Fifty Sprague-Dawly male rats aging 8 months(older rats) and 2 months(younger rats) were used as experimental animal. Zinc deficient diet(1.1ppm) and normal zinc diet(36.5ppm) were used as experimental diets. Rats in each age group were divided into zinc deficient(ZnDF), zinc pair-fed(ZnPF) and zinc ad-libitum(ZnAL) to remove the variances of food intake. After 4 weeks of experimetal period, rats were sacrificed. Thiobarbituric acid reactive substance(TBARS) levels in plasma and liver, lipofuscin and conjugated diene levels in liver were measured as lipid peroxide index. Food intakes of all groups were not different because zinc deficiency did not reduce food intake in ZnDF group. Younger rats gained weight continuously, while older rats lost weight in the begining of experiment and regained afterwards. In older rats, serum zinc level was decreaed while plasma TBARS. level was increased in ZnDF group. In younger rats, plasma TBARS concentration was increased in dietary zinc deficient rats although serum zinc concentration was not reduced. Liver zinc concentration was significantly higher in older rats comparing to younger rats. However, there was no difference among the three dietary groups. Liver TBARS level was not different by age or dietary zinc level. However it was tended to be higher in older rats. However there was no difference by the dietary zinc level. In both age groups, ZnDF group significantly increased plasma TBARS levels, which suggested dietary zinc deficiency could increase lipid peroxidation in part. Significantly higher levels of lipofuscin and conjugated diene in older rats suggested lipid peroxidation was accelerated by aging.

• Korean Journal of Pharmacognosy
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• v.34 no.2 s.133
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• pp.172-178
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• 2003

This study was done to investigate the protective effect of Alnus japonica Steude on hepatotoxicity in carbon let-rachloride $(CCl_4)$ intoxicated rats. Alnus japonica Steud was extracted with methanol and fractionated with hexane, chloroform, ethylacetate, butanol and water. Rats were treated with those orally once a day for 6 days. The activities of aminotransferase and ${\gamma}-glutamyltranspeptidase$ and contents of cholesterol, TG and hepatic lipid peroxide in butanol fraction pretreated rats were significantly decreased compared to the only $CCl_4$ treated rats but the content of glutathione was significantly increased compared to the only $CCl_4$ treated rats. Also activities of hepatic superoside dismutase, catalase, glutathione perpxidase in butanol fraction pretreated rats were signigicantly decreased compared to the only $CCl_4$ treated rats. These result indicated that butanol fraction of Alnus japonica Steude showed hepatoprotective effect in carbon tetrachloride intoxicated rats.

• YAKHAK HOEJI
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• v.35 no.4
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• pp.326-331
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• 1991

Brain serotonin and its utilization was investigated on stressed rats after feeding high tryptophan diet for a month. High tryptophan fed rats displayed significantly higher level of serum tryptophan, brain tryptophan, serotonin (5-hydroxytryptamine; 5-HT) and 5-hydroxyindoleacetic acid (5-HIAA) than the control diet fed rats. When rats were treated with 3 hour immobilization (IMMB) stress, serotonin turnover was slightly increased, but not statistically significant, in control diet group rats. However in high tryptophan diet rats, 3 hr IMMB stress resulted in statistically significantly (p<0.05) decreased the serum tryptophan, brain tryptophan and 5-HT level. The concentration of 5-HIAA was significantly increased indicating accelerated utilization of the brain 5-HT of the high trp. fed rat. The utilization pattern of the serotonin was found to be similar among young and adult rats. Rats on a tryptophan enriched diet displayed higher coping ability to the stress as they exhibited smaller increment of corticosterone level. A possble involvement of opioid system was suggested in serotonin utilization by measuring total $^{3}$[H]-naloxone binding in brain.

• Journal of Nutrition and Health
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• v.25 no.5
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• pp.397-403
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• 1992

This study was performed to investigate the effect of dietary magenesium on stress reactions in rats having abdominal surgery. Sixty three male rats of sprague-dawley strain were blocked into 3 groups : rats fed regular magnesium (0.05% Mg: control) rats receiving regular magnesium with surgery(Mg-adeq : S) Five weeks after feeding abdominal surgery was performed and randomly chosen 7 rats from each group were sacrificed on 1, 3 and 5 days after surgery. Te following were found ; 1) Rats fed marginal magnesium showed significantly elevated urinary urea nitrogen urinary potassium and plasma glucose compared controls only one day after abdominal surgery but not 3 days or 5 days after surgery 2) Rats fed adequate magnesium did not show any significant change in metabolic stress indicator after surgery. 3) Plasma free fatty acid and cortisol level were not different among groups. 4) Decreased plasma magnesium and potassium level were found in rats fed marginal magne-sium and sacrificed one day and three days after surgery.